Changes in Salmonid Communities Associated with Pesticide Runoff Events

Abstract

Two agricultural runoff events involving the pesticide azinphos-methyl occurred in July 2002 on the Wilmot River, Prince Edward Island, Canada, resulting in the death of thousands of fish. The fish communities from three sites on this river had been sampled in 2001, permitting comparisons of brook trout (Salvelinus fontinalis) and rainbow trout (Oncorhynchus mykiss) populations before and after the events. Samples taken immediately after the runoff events suggested that brook trout suffered higher mortality than rainbow trout. Young-of-the-year fish were more affected than older age classes for both species. Sampling in 2003, a year after the pesticide runoff events, revealed salmonid communities that were still skewed towards rainbow trout, and a decrease in the 1+ age class density (2002's young of the year) at affected sites. These results suggest a differential effect of the pesticide azinphos-methyl on salmonid species and age classes under natural conditions, and a subsequent change in population and community structure. The possibility of these pesticide runoff events selecting for rainbow trout, an exotic species, is a consideration in management of agriculturally impacted rivers.

Azinphos-methyl and chlorpyrifos, alone or in a binary mixture, produce oxidative stress and lipid peroxidation in the freshwater gastropod Planorbarius corneus

“…These insecticides can reach watercourses via runoff and spray drift and adversely affect aquatic invertebrate and vertebrate non-target species (USEPA, 2001;Gormley et al, 2005;Anguiano et al, 2012;Williams et al, 2014).…”

The effect of a large-scale irrigation scheme on the fish community structure and integrity of a subtropical river system in South Africa

“…A study in Mexico assessed the fish community of a reservoir following a spill event (Favari et al, 2002). Another study done on trout in the USA by Gormley et al (2005) before and after an agricultural runoff event of azinphosmethyl indicated that brook trout (Salvelinus fontinalis) mortality was higher than the mortality for rainbow trout (Oncorhynchus mykiss) directly after the runoff event. The younger age classes for both fish species were also more affected than the older age classes.…”

Distribution of haemic neoplasia of soft‐shelled clams in Prince Edward Island: an examination of anthropogenic factors and effects of experimental fungicide exposure

“…In addition, farm pesticides on PEI have been linked to a number of fish mortalities on PEI (Mutch et al . ; Gormley, Teather & Guignion ). The correlation between potato acreage and forest coverage with HN in our study compared closely with the correlation made by Farley et al .…”